Compressed air operated catapult system for ejection seat trainers



Aprll 2 1970 H. B. WHITMORE ETAL 3,507,264

COMPRESSED AIR OPERATED CATAPULT SYSTEM FOR EJECTION SEAT TRAINERS Filed Dec. 19, 1967 INVENTO S.

HENRY .3. wfi/rMazei, BYE/{A051, w.

United States Patent US. Cl. 12411 5 Claims ABSTRACT OF THE DISCLOSURE An air operated catapult system for ejection seat trainers having a compressed air source operatively connected to an accumulator section which feeds into a catapult cylinder containing a piston. A pair of double balance valves are positioned in a control cylinder such that when pressure is introduced to a valve opening piston, the balance valves open and allow the air from the accumulator to enter the catapult cylinder and force the piston attached to the ejection seat upward. The system is deactivated after the seat has been given the driving force and moved a short distance upward.

BACKGROUND OF THE INVENTION This invention relates to an air operated catapult system for ejection seat trainers and more particularly, the invention is concerned with providing a low cost air operated catapult piston and cylinder arrangement for use as an alternate system on ejection seat training devices.

The use of ejection seats as safety devices is well known in the art. Such ejection seats are used generally in connection with military aircraft where it is desired to propel the pilot away from the aircraft to safe parachute height, even when ejection is initiated at ground level as in take-off or landing situations. The catapults used to energize rnost presently known ejection seats are actuated by explosives and rocket motors. Although these systems operate satisfactorily under actual danger and disaster conditions, their use for training purposes raises many undesirable and potentially dangerous situations.

In an explosive type catapult system, there is a requirement for the handling and storage of ammunition which is always hazardous regardless of the precautions taken. Also, once the explosives has been fired, the subsequent ejection cycle is virtually uncontrollable. The operation of the explosive system requires the manpower of three men and produces corresponding maintenance problems associated with explosive charges. Other drawbacks to the use of the explosive system for ejection seat training purposes are noise, high cost of ammunition, danger of premature firing and the frequency of repairs and replacement required as well as the relatively high initial cost of the system.

Accordingly, it is an object of the present invention to provide a low cost, practical and economical ejection seat system suitable for training purposes.

Another object of the invention is to provide an ejection seat trainer which improves training eife'ctiveness and add-s to the safety of the subject by making the ejection seat travel more fully controllable.

Still another object of the invention is to provide an ejection seat training system which utilizes an air operated catapult as the energizing source. The compressed air system provides controlled distance and G force application. 1

A further object of the invention is to provide an ejection seat having an air operated catapult system which is easily adaptable for installation on a conventional "ice ejection seat trainer without extensive modifications being required.

A still further object of the invention is to provide an ejection seat trainer having a compressed air catapult system which is relatively simple in construction of readily available materials thereby greatly reducing the operational and maintenance costs as well as reducing the manpower requirement during actual use.

These and other objects, features and advantages will become more apparent after considering the detailed description that follows taken in conjunction with the illustrative embodiment in the accompanying drawing.

DESCRIPTION OF THE DRAWING DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawing, the compressed air operated catapult system for ejection seat trainers according .to the invention includes a catapult cylinder 13 having a catapult piston 15 slidably mounted therein. The piston rod 17, in practice, is attached to any suitable ejection seat of which there are many well known types. The lower end of vertical cylinder 13 is operatively connected to a perpendicularly mounted control cylinder 19 having a valve opening piston 21 mounted in one end thereof. An accumulator section 23 is operatively connected to and disposed below the cylinder 19. A solenoid valve 25 is interposed in the air line 27 which connects the accumulator section 23 to a chamber in front of the valve opening piston 21. The compressor 29 provides a 200 psi. pressure with adequate volume and flow through the air supply line 3.1 to the catapult accumulator 23.

A pair of double balance valves 33 and 35 are positioned within the cylinder 19 on either side of the opening between the cylinder 19 and the cylinder 13. A pair of valve seats 37 and 39 interact with the valves 33 and 35, respectively, to seal oil? the flow .of air to the cylinder 13 when in the closed position. A valve spring 41 located in the end of the cylinder 19 opposite the valve opening piston 21 serves as a biasing element to urge the valves 33 and 35 into their closed position. The double balance valves 33 and 35 and the valve opening piston 21 are mounted on the common shaft 43 and move therewith within the control cylinder 19. Thus, when the piston 21 moves in either direction, the valves 33 and 35 also move the same distance in the same direction.

MODE OF OPERATION The hereinbefore described alternate catapult system is relatively simple to operate. The compressor 29 is a standard machine capable of providing 200 psi. pressure with adequate volume and flow. The pressure line 31 conveys pressure from the compressor tank 45 to the catapult accumulator section 23. This pres-sure is applied to one side of the balance valve 33 urging it closed and to the other side of balance valve 35 urging it open. Since both valves 33 and 35 are on a common shaft, the total effect of the pressure is neutralized and the net resultis zero movement. Only the tension of the valve closing spring 41 is required to keep the valves closed.

The solenoid valve 25 which operates to control the flow of air from the compressor tank 45 to the accumulator section 23, is the actuation device for the system and may be electrically matched into the existing firing and. safety feature of a conventional ejection seat system without modification. When subject riding the seat has completed standard ejection sequence already established foreach particular type of trainer and pulls the firing trigger, the solenoid valve 25 opens and allows pressure from catapult accumulator 23 to enter the chamber in front of valve opening piston 21 which is mounted on common shaft 43 along with valves 33 and 35. The air pressure acting on piston 21 exerts a greater force than that of valve spring 41 causing the piston 21 along with rod 43 to move toward the center of the cylinder 19 and allowing instant opening of the double balance valves 33 and 35.

With the balance valves 33 and 35 in the open position, the air from the accumulator section 23 rushes into the cylinder 19 and then into the catapult cylinder 13 forcing the piston 15 upward within the cylinder 13. The rod 17 which would be operatively attached to the ejection seat moves the seat and subject the required distance at the proper velocity. When the catapult piston 15 has traveled approximately two inches upward through cylinder 13, a pressure conservation switch (not shown) is activated by a bar and micro switch arrangement on the seat as it moves up the ejection track causing the solenoid valve to close. This cuts off the air supply to the valve opening piston 21 causing the valve closing spring 41 to urge the balance valves 33 and 35 against their respective valve seats 37 and 39 thereby shutting off the supply of air entering catapult cylinder 13. Since only a relatively small amount of air is needed to accomplish the operation, the drop in total pressure in the accumulator 23 amounts to only 10 to 20 psi. and recycling time required to build up the air pressure to the required level is cut to a minimum.

Although the invention has been illustrated in the accompanying drawing and described in the foregoing specification in terms of a preferred embodiment thereof, the invention is not limited to this embodiment or to the particular use mentioned. It will be apparent to those skilled in the art that our invention can be used to control the distance of ejection on the trainer regardless of the weight of the subject, thus reducing the possibility of injury due to over-firing. Also, it should be understood that various changes, alterations, modifications and substitutions, particularly with respect to the construction details, can be made in the arrangement of the several elements without departing from the true spirit and scope of the appended claims.

Having thus described our invention, what we desire to secure by Letters Patent of the United States is:

1. A compressed air operated catapult system for an ejection seat trainer, said catapult comprising a catapult cylinder vertically oriented, a catapult piston disposed in the lower portion of said catapult cylinder, said piston being dimensioned for slidable movement in said catapult cylinder, a piston rod fixedly attached to and extending upwardly from said piston, a control cylinder horizontally oriented and in a T-shaped connection with said catapult cylinder, said control cylinder extending outwardly on either side of said catapult cylinder, an accumulator section having a first outlet operatively connected to said control cylinder on one side of: said catapult cylinder remote from the catapult cylinder and a second outlet operatively connected to said control cylinder on the other side of said catapult cylinder remote from the opposite side of the catapult cylinder, said accumulator having a compressed air source connected thereto, and valve means disposed in said control cylinder for regulating the flow of compressed air from said control cylinder to said catapult cylinder.

2. The catapult system defined in claim 1 including an ejection seat, a firing trigger positioned to be energized by a subject riding in said ejection seat, wherein a solenoid control valve is interposed in an air conductor line between said accumulator and one end of said control cylinder, said solenoid valve being responsive to an electrical signal originating at said firing trigger to allow the flow of air into said control cylinder thereby opening said valve means and allowing the flow of air to said catapult cylinder. 1

3. The catapult system defined in claim 2 wherein a valve opening piston is slidably disposed in one end of said control cylinder, said solenoid control valve operating to regulate the flow of air to a chamber in front of said valve opening piston, a shaft extending from said valve opening piston through said control cylinder, said valve means being operatively connected to said shaft, the introduction of compressed air into the chamber in front of said valve opening piston causing said piston and shaft to move in a lateral direction.

4. The compressed air operated catapult system defined in claim 3 wherein said valve means for regulating the flow of air to said catapult cylinder includes a pair of double balance valves disposed in the central portion of said control cylinder and fixedly attached to the shaft extending from said valve opening piston and movable therewith, one of said balance valves being located on one side of said catapult cylinder and the other of said balance valves being located on the other side of said catapult cylinder, the compressed air from said accumulator section operating to urge one of said balance valves toward the closed position while simultaneously urging the other of said balance valves toward the open position, the total effect being opposite pressures which cancel each other resulting in zero movement of the balance valves with respect to each other.

5. The compressed air operated catapult system defined in claim 4 wherein a valve closing spring is disposed in the other end of said control cylinder, said valve closing spring maintaining said balance valves in the closed position preventing the flow of compressed air from the control cylinder to the catapult cylinder until said solenoid control valve opens to allow compressed air to enter the chamber in front of said valve opening piston, the force exerted by the compressed air in the chamber overcoming the effect of said valve closing spring causing lateral movement of said valve opening piston and shaft producing a corresponding movement of said balance valves to the open position to allow the !full flow of air from the control cylinder to the catapult cylinder.

US. Cl. X.R. 60-26.l 

